(1) 血清sialic acidの工業慢性中毒指標としての有用性を,工業毒物の内,互に生体への障害部位を異にする一方生体内での代謝および排泄速度に著るしい差異が認められないと予想される四塩化炭素,二硫化炭素およびacrylonitrileをもちいて投与毒物に対する反応の鋭敏性および変動の定量性の二点より検討した。 名毒物共血清sialic acidの中毒群平均値は投与開始後1&2週間以内に対照群平均値95%信頼限度を超える著明かつ安定した上昇を示し,変動出現の時期は従来これらの慢性中毒指標として用いられてきたhematocritおよびhemoglobin等血液性状あるいは体重増加と比較してより早期であった。またそのさいの血清sialic acidは,各群共,累積投与量の平方根に対して直線的に増加することが認められた。 (2) さらに血清sialic acidの変動の毒物投与によるbody burdenに対する定量性が,累積投与量を各々の相対的毒性の強度で標準化した値の平方根に対する直線性より明らかになり,血清sialic acidが中毒状態における生体のimpairmentを定量的に評価する可能性が示唆された。 (3) 血清sialic acidの変動が,常に〓紙電気泳動法による血清蛋白分画のalbuminの減少とα_1-, α_2-あるいはβ-globulinの増加を伴なうことより,前者の変動は血清glycoproteinに基くものと思われる。 (4) 脳下垂体前葉および副腎皮質系に対する典型的stressorである寒冷および温熱に暴露した家兎群で,血清sialic acidの著明な上昇を認めたことにより,その変動機構の一環として,脳下垂体-副腎皮質系の介在を否定できない。従って,さらに広範囲な諸種の環境因子による血清sialic acidは変動の予想される。 (5) 以上の結果,血清sialic acidは,産業慢性中毒の統計的判別指標として有用であり,とくに作業環境に2種類以上の異種の中毒物質が共存する場合や寒冷あるいは温熱等の物理的異常環境下における中毒状態の指標として一層有効性を発揮することが期待される。

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For elucidation of the relationship between the toluene concentration in the air and the amount of hippuric acid excreted in the urine as a metabolite, expermiments were carried out in an exposure chamber. We made use of two groups of volunteers as experimental subjects: one i.e. the three-hour exposure group which was exposed to 100 p.p.m. 200 p.p.m. toluene for three hours, and the other i.e. the seven-hour exposure group which was exposed for three hours in the morning and for four hours in the afternoon with one hour intermission in between. Results obtained are as follows. 1) Urinary excretion of hippuric acid during and after the exposure. In the case of seven-hour exposure group, the excretion increased rapidly from the beginning to two hours of exposure. Similar results were obtained in the three-hour exposure group. During one hour intermission a decrease was observed. In the afternoon, a similar excretion curve to that of the morning was obtained except that the urine collected at the beginning of the exposure showed a relatively high level. The maximum concentration of hippuric acid was observed in the urine immediately after leaving the exposure chamber or one hour later; and 18 hours later the concentration recovered to the normal level. 2) Relationships between toluene density in the air and the concentration, the amount of excretion per minute, and the total excreted amount of hippuric acid in the urine. Values of these three items as to the urinary hippuric acid were proportional to the toluene density in the exposure chamber, although there was a tendency that the ratios of these three items to the toluene density in the volunteers exposed to 200 p.p.m. toluene was a little less than those exposed to 100 p.p.m. The excretion rate of toluene in the urine as hippuric acid, calculated by Patty's equation, was 63-66 per cent in the three-hours exposure group and 74-82 per cent in the seven-hours exposure group. 3) Maximum allowable concentration (M.A.C.) or maximum allowable excretion per minute (M.A.E.) of the urinary hippuric acid. M.A.C. (mg/ml) corresponding to 200 p.p.m. of toluene was 3.74 (3.69) in the morning urine, 8.19 (7.84) in that of the afternoon, and 5.74 (5.54) throughout the working time. M.A.E. (mg/min) corresponding to 200 p.p.m. of toluene was 3.13 (3.06), 4.61 (4.51), and 3.77 (3.78) respectively. Screening level of the concentration (mg/ml) of urinary H.A. corresponding to 200 p.p.m. of toluene was 3.15 (2.83), 5.57 (5.83), and 5.14 (4.73) and that of excretion (mg/min) was 2.77 (2.67), 3.81 (3.55), and 3.05 (3.14), taken as minus value u2=1/(N-1)Σ^^N__(i=1)(xi-x^^-)2. M.A.C. corresponding to 200 p.p.m. of toluene, corrected to the specific gravity of the urine at 1.024 according to Elkins, was 3.71 (3.63), 5.85 (5.89), and 5.99 (5.76), and the screening level 3.04 (3.04), 4.61 (4.99), and 4.80 (4.73). These values were calculated from interpolation along the line indicating the relation between the toluene concentration and the amount of the urinary hippuric acid, and those in parenthesis were obtained from the following calculation; Regression line was made from the hippuric acid concentration after inhalation of 100 p.p.m. and 195 p.p.m. toluene. Y-y^^-=(Σ(x=x^^-)(y-y^^-))/(Σ(x-x^^-)2)(X-x^^-) where x^^-=(100+195)/2p.p.m. y^^-=1/2(Σ H.A. mg/ml at 100 p.p.m./N+Σ H.A. mg/ml 195 pp.m./N) N: number of cases calculated Using these regression line, we found that the amount of hippuric acid at 200 p.p.m. of toluene was assessed by extrepolation. Excretion per minute also by the similar method is indicated as values in the parenthesis. 4) Normal values of the urinary hippuric acid. Hippuric acid concentration, excretion per minute, and total excretion in the diurnal urine of healthy persons, was 0.27 mg/ml, 0. [the rest omitted]

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For elucidation of the relationship between the m-xylene concentration in the air and the amount of m-methyl hippuric acid (m-M.H.A.) excreted in the urine as a metabolite, experiments were carried out in an exposure chamber. The volunteers were exposed to m-xylene at 200 p.p.m. for three hours in the morning and for four hours in the afternoon with one hour intermission in between. Results obtained were as follows. 1) Course of the excretion of urinary m-M.H.A. The excretion increased rapidly from the beginning to two hours of exposure. During the intermission of one hour a decrease was observed. In the afternoon a similar excretion curve to that of the morning was obtained, except that the urine collected at the beginning had a relatively high level of m-M.H.A.. The concentration recovered to the zero level after completion of exposure for 18 hours. 2) Maximum allowable concentration (M.A.C.) and maximum allowable excretion per minute (M.A.E.) of urinary m-M.H.A. M.A.C. of m-M.H.A. (mg/ml) corresponding to 200 p.p.m. of m-xylene was 3.59 in the morning urine, 5.79 in that of the afternoon, and 4.56 throughout the working time. M.A.C. corresponding to 200 p.p.m. of m-xylene and corrected to the specific gravity of 1.024 of the urine by Elkins, was 3.19, 5.58 and 5.32 respectively and M.A.E. (mg/min) corresponding to 200 p.p.m. of m-xylene was 3.89, 4.44 and 4.10. Screening level of the concentration of urinary m-M.H.A. (mg/ml) corresponding to 200 p.p.m. of m-xylene was 2.94, 4.88 and 4.07 respectively, that of concentration (mg/ml) corrected to the specific gravity of 1.024 was 2.73, 4.25 and 5.08 and that of excretion (mg/min) was 3.00, 3.34 and 3.26, taken as m-u value (u²=1/(N-1)Σ^^N__(N-1)(x_i-x^^-)²). These values were calculated by interpolation on the line indicating the relation between m-xylene concentration and the amount of urinary m-M.H.A. 3) Physiological changes In one volunteer out of five the decrease in the pulse rate and prolongation of the reaction time were recognized. Note: Level of 200 p.p.m. of xylene corresponds to TLV by ACGIH

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We carried out a survey by means of questionnaires to know the actual attitude of supervisors in all the sections on the physical fittness requirement of workers. The items were height, weight, chest girth, grip strength, vital capacity, visual acuity, use of glasses, color discrimination, hearing, loss of fingers, function of upper extremities, functions of lower extremities and of waist, physique in general, obesity, and hypersensitivity. Results obtained were as follow: (1) Only supervisors in the section of forging required that workers should have the physique tolerable to heavy muscular work. The values required by most supervisors as the lowest limits of height, weight, chest girth, grip strength, and vital capacity were those in the range of which about 95% of the values of all adult male Japanese are included. (2) As for visual acuity, color discrimination, loss of fingers, and functions of upper extremities and of lower extremities, the requirement was generally severe. (3) About 70% of the supervisors answered that obese workers were undesirable or to be rejected, but a few of them put the highest limit on the weight of workers. (4) Workers with hypersensitivity were undesirable in the image of most supervisors.

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